Attachment for abney levels



June 26,1928. 1,675,158

E. C. BUCK ATTACHMENT FOR ABNEY LEVELS Filed April 10, 1926 Qwwentoz Z6i EDWARD Cfiuc/c Patented June 26, 1928.

UNITED STATES EDWARD C. BUCK, OF PORT OF SPAIN, TRINIDAD, BRITISH WESTINDIES.

ATTACHMENT FOR AB'NEY LEVELS.

Application filed April 10,

an improved attachment for use with the ordin-ary Abney level commonlyemployed by surveyors and engineers whereby such type of level equippedwith my attachment may be utilized especially by mariners for taking thealtitude of the sun or any of the heavenly bodies as is customarily donewith the sextant. I

The objects of my invention are, among other things, to provide animproved form of attachment to be used with the Abney level, moreparticularly for use by the mariner in sighting the sun, such attachmentembodying a disk wheel carrying aseries of varlably tinted glass platesarranged over theopen end of the sight tube so that the suns rays shallbe dimmed sufficiently to enable the mariner to make carefulobservations without blinding or inconvenience from the intensity of thesuns rays. Since under different weather conditions, the suns rays areof variable brightness, I have'provided this novel attachment whichenables the observer to place instantly between his eye and'the sun aglass of suitable translucency to enable the mariner to make accurateand careful observations by employing the Abney level.

Further features of invention will hereinafter be described and thenparticularly pointed out in the appended claims.

In the drawin s showing an embodiment of my inventionfFig. 1 is a sideelevation of the Abney level equipped with my improved attachment;

Fig. 2 is another side view partly in longitudinal vertical sectionshowing the arrangement of the difierent parts;

Fig. 3 is an end view looking from the left.

in Fig. 1

Fig. 4 is a sectional View taken on the line 44 of Fig. 2; and

Fig. 5 is a detail view of the disk wheel having sectors formed ofglasses of varlable density or translucency.

Similar numerals refer to similar parts throughout the several figures.

Referring to the drawings the tubular body 6 of the level forming thesighttube is preferably square in cross-section (Figs. 3 and 4) and isprovided with the telescopic eye-piece 7 adjustably secured at one end,while the full open square bore end 8 is located at the opposite endfrom the eye-piece 7 as shown in Fig. 3. Attached to the side of thebody 6 by the screws 9 is the fixed Vernier scale 10 1926. Serial No.101,066.

marked on for angles up to about 90 (Fig. 1). On the inner side of thecross-bar 11 of .10. The scale 18 moves with the spirit level tube 14,both devices rotating on the bearings 17'back of the thumb-screw 16. Thehole 19 is formed in the top of the tubular body 6 directly below thetube 14 and inside the tu bular body 6 below the hole 19 is the inclinedrectangular mirror 20 which extends sidee wise half way across the boreof the body,

6 (Fig.4) so as to enable the observerto look past themirror 20 towardthe desired object. The cross-wire 21 extends across the open square end8 of the tubular body 6 as shown in Figs. 2, 3 and 4. To obtain anobservation, observer looks through the eye-piece 7 at the desiredobject (for example the sun) and then turns the spirit level tube 14 onits bearings 17 until the refiection of thebubble 15 appears on themirror 20; when the crosswire 21 cuts" the object observed and also thereflection of the bubble 15 appearing on the surface of the mirror 20,the observation has been completed and the degrees of elevation ordepression may be read on the Vernier scale 10 affixed to the tubularbody 6. All these parts have been heretofore used in constructing t-he Abney level and do not in themselves constitute my invention.

the scale 10 is movable plate 12 having two brackets-13 which supportthe ends of the Near the open end 8 I have secured the bracket 22: tothe tubular body 6, the

bracket 22 carrying the projecting stud 23 v on which is rotatably vmounted the disk Wheel 24 secured in any'predetermined position by thethumb-screw 25 as shown in F i'gs. 1,' 3 and 4. The disk wheel24comprises a series of sectors 26, 27, 28 and 29 (Fig. 5)

each sector being composed of variably tinted glasses of differentdegrees of translucency. The

disk wheel 24 may be revolved on the stud 23'so as to bring any ofthedifferent sectors 26, 27 28 and 29 to cover the half of the open end 8that isnot in alinement with the mirror as shown in Figs. 3 and 4. Inuse the disk wheel 24 is rotated until a suitably tinted sector (2629)for the conditions of work has been brought across half the open end 8.

Only one-half of the open end 8 need be protected by one of the glasssectors (26-29) since the mirror 20 efi'ectively shuts off any rays oflight in the other half of the tube bore. As a matter of practice themirror 20 is formed as a tube which may be inserted at the open end 8and withdrawn therefrom at will to suit conditions of use. Since thebrightness or intensity ofthe suns rays is likely to vary momentarilydue'to passin clouds or for other reasons the varia'b' y tinted glasssectors of the revolving disk wheel 24 enables the observer to make thenecessary observations without interruption or inconvenience.

For stellar observations I have provided a small electric bulb light 30removably mounted on the battery 31 which is enclosed in thehousing '32attached to the to side of the tubular body 6 as shownin igs. I and 2.The front end of the housin carriesthe glass plate 33 behind whidh isthe conical reflector 34 surrounding the bulb 30 as shown in Fig. 2. Theslide switch 35 having the knob 36 projecting through the slot 37 in thetop otthe housing 32 controls the lighting of the bulb 30 in the usualman ner. WVhen making observations at night with this lightingattachment, the disk wheel 2%} is removed from the stud 23 so that anuninterrupted view maybe obtained throu h the eyepiece, 7 by aid ofthelight from t e bulb '30 in reflecting the bubble 15 on the mirror 20 ashas been hereinbefore described.

While the construction herein shown and described embodies my inventionin a preferred form, it will be understood that changes and variationsmay be made in the various parts without departing from' the principlesand scope of my invention or sacrificing itschief advantages.

1' claim as my invention 1. An attachment. for an Abney level sight tubehaving a rectangular mirror. po

-sitioned within the bore ofthe tube with its face inclined away fromthe open end of said tube, and' covering substantially onehalfof theopen end of said tube, comprising a tinted glass piece secured oversubstan: tially the one-half of the open end of'said tube out ofalignment with said mirror.

2, An attachment for an Abney level sight tube having a rectangularmirror positioned within the bore of the tube with its face inclinedaway from the open end of said tube, and covering substantially one halfof the open end of saidtube, comprising a series of variably tintedglass pieces selectively secured over substantially the one-half of theopen end of said tube out of alignment with said mirror.

3..An attachment for an Abney level sight tube having a rectangularmirror positionedwit-hin the bore of the tube with its face inclinedaway from the open endof saidtube, and covering substantially onehalf ofthe open end of. said tube, comprising a disk wheel having a pluralityof sectors of variably tinted glass rotatably secured over that portionof the open end of saidtube out of alignment with said mirror wherebyany of said sectors may be brought in operative alinenient with saidopen portion extending through the tube.

4:. An attachment for an Abney level sight tube having a rectangularmirror positionedwithin the bore of the tubewith its face inclined awayfrom the open end of; said tube, and coverin substantially onehalf. ofthe 0 en end 0 said tube, comprising a sk W e l ha a p ral se tors of.variably tinted glass rotatably secured over that portion of the openend of said tube out of ali ment with said mirror whereby any of saisectors may be brought in operativealinement with aid Open portionextending. through the tube and means for holdingsaid wheel in anypredetermined position.

5. An attachment for an Abney level sight tube havim a rectangularmirror positioned within t e boreof the tube with its face inclined.away from the open end of said tube,and coverin substantially one halfof the 0 en end. o said tube, compris; ing a w eel having plurality ofsectors of variably tinted glass rotatably se cured overthat portion ofthe. open end ofsaid tube. out of ali ment with said mirror whereby anyof sai sectors may be brought in operative alinement, with anunobstructed substantially one-half portion extending through the boreof the tube to the eyepiece e 6. An attachment for an Abney. level sighttube havin a rectangular mirror positioned within t e bore of the tubewith its face inclined away from the open end of said tube, and coverinsubstantially one half of the open end 0 said tube, comprisinga diskwheel having a plurality of.sectors of variably tinted glass rotatablysecured overthat portion of, the open endofsaid tube out of. alignmentwith said mirror whereby any of said sectors may be brought ino erativealinement with an unobstructed su stantially one-half portion ex tendingthrough the bore of the tubetothe eyepiece and means fonholding saidwheel in any predetermined position.

7. In an Abney level sight tube having a bore substantially square incross-section, in-combination, a rectangular mirror positioned in saidbore to cover substantially one} half of the open end oftsaidtubejwithits face inclined away from said open end, and a disk wheel having aplurality of sectors of variably tinted glass rotatably secured over theunobstructed by. said mirror open end of the tube in operative alinementwith the eye-piece opposite said open. end.

8. In an Abney level sight tube having a bore substantially square incross-section, in

combination, a rectangular mirror positioned of variably tinted glass oflike size rotat ably secured over the unobstructed by said mirror openend of the tube in operative 10 alinement With the eye-piece oppositesaid open end whereby said unobstructed onehalf portion is substantiallycovered by any one of said sectors.

EDWARD o. BUCK.

